• 关键词：南水北调  总干渠  溶解性有机质(DOM)  高锰酸盐指数  耗氧量

• 基金项目：中国科学院重点部署项目（No.ZDRW-ZS-2017-3-5）；国家水体污染控制与治理科技重大专项课题（No.2017ZX07108-001）；环境模拟与污染控制国家重点联合实验室（中国科学院生态环境研究中心）专项经费资助项目（No.18Z02ESPCR）

• 范傲翔
• 1. 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085;2. 中国地质大学(武汉)环境学院, 武汉 430074

• 王智鹏
• 1. 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085;2. 中国科学院大学, 北京 100039

• 王超
• 长江水资源保护科学研究所, 武汉 430051

• 尹炜
• 长江水资源保护科学研究所, 武汉 430051

• 李立青
• 中国地质大学(武汉)环境学院, 武汉 430074

• 张洪
• 1. 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085;2. 中国科学院大学, 北京 100039

• 摘要：为揭示南水北调总干渠水体耗氧物质的种类及其潜在来源，对总干渠沿线进行了水样采集，并分析了总干渠水体的耗氧因子的分布及其耗氧成因.结果表明，从渠首到北盘石监测断面，高锰酸盐指数低于国家地表水Ⅰ类水质标准值（2 mg·L^-1），北盘石以北（除惠南庄断面）几乎全部高于2 mg·L^-1.溶解性有机质（DOM）、NH₃-N和NO₂^--N浓度在总干渠沿程呈波动特征；Fe²⁺和Mn²⁺浓度在北盘石以南断面较为稳定，之后分别呈降低和升高趋势.基于上述物质耗氧的化学计量关系，DOM耗氧量均值为1.86 mg·L^-1，对高锰酸盐指数的平均贡献率超过了70%；无机物质中NH₃-N耗氧量最高，平均为0.134 mg·L^-1，而NO₂^--N、Fe²⁺及Mn²⁺的耗氧量均低于0.1 mg·L^-1.对主要耗氧因子DOM的三维荧光分析结果表明，荧光指数（FI）、自生源指数（BIX）、腐殖化指数（HIX）变化范围分别为1.68~3.62、0.68~1.22、1.47~3.04，表现出较强的自生源特征，DOM内源输入占比达到了71.63%~80.94%，并且在藻类爆发期，藻密度突变点与高锰酸盐指数的突变点高度吻合.上述结果表明主要来源于自身藻类和微生物的DOM是导致总干渠沿程高锰酸盐指数升高的主要原因，干渠自身生物化学过程对水质的影响值得长期关注.

• Abstract：In order to determine the oxygen-consuming substances and trace their possible sources of the main channel of Middle Route of South-to-North Water Diversion Project, water samples were collected from sections along the main channel, and the distribution of the oxygen-consuming factors and their causes were analyzed. Results showed that the permanganate index in the main channel is under the threshold level of Grade Ⅰ(2.0 mg·L^-1) from the source to Beipanshi monitoring cross section, However, almost all (except the Huinanzhuang) were higher than 2.0 mg·L^-1 for the northern of the Beipanshi sections. The concentrations of dissolved organic matter (DOM), NH₃-N, and NO₂^--N in the main channel displayed fluctuation characteristics along the route. The concentration of Fe²⁺ and Mn²⁺ was also stable in the south of Beipanshi section, and then showed a downward and upward trend. Based on the stoichiometry of oxygen consumption of the substances above, the average oxygen consumption for DOM was 1.86 mg·L^-1, accounting for more than 70% of permanganate index. For these inorganic substances, the oxygen consumption of NH₃-N was highest, which consumed 0.134 mg·L^-1 oxygen averagely, while the consumption of NO₂^--N, Fe²⁺, and Mn²⁺ all less than 0.1 mg·L^-1. Three-dimensional fluorescence analysis revealed that, the ranges for Fluorescence Index (FI), Biological Index (BIX), and Humification Index (HIX) were 1.68~3.62, 0.68~1.22, and 1.47~3.04, respectively, which showed strong autogenic characteristics. The proportion of internal input of DOM ranged from 71.63% to 80.94%, and the mutation point of algal density was highly consistent with that of permanganate index. This study indicated that the DOM mainly derived from its own algae and microorganisms might be the probable reason for the increase of permanganate index along the route of the main channel, and the influence of its own biochemical process on water quality deserves long-term attention.

• Key words：South-to-North Water Diversion Project  main channel  dissolved organic matter(DOM)  permanganate index  oxygen consumption

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